This article is about UPS/DC Battery Rectifier / Charger Material Selection & Application Design Notes for Commercial Buildings,
UPS/DC Battery Rectifier / Charger Material Selection & Design Notes
UPS/DC Battery Charger Material Checking
| QC Before Installation- Battery Rectifier / Charger shall conform to all applicable requirements, standards, and specifications prior to release to be used as part of work. |
| Incoming Battery Rectifier / Charger shall be visually inspected for damage / defects occurred during transportation and conformance to all applicable requirements. |
| Battery Rectifier / Charger shall be new and unused. |
| Battery Rectifier / Charger shall be in accordance with the Saudi Aramco-approved project-specific design drawings, diagrams, schedules, lists, databases, and associated design documents. |
| Check that the Contractor or it’s approved third party inspector performed the quality activities at the supplier and sub-supplier locations as required by the inspection level assigned for the materials and equipment identified in Inspection Requirements. |
UPS/DC Battery Rectifier / Charger Application Design Notes
| If one UPS unit is taken out of service, it shall automatically synchronize and reconnect to the load bus when placed back in service with no disturbance to the other UPS or the load. |
| UPS Systems “A” and “B” shall have separate battery banks such that each battery bank shall be sized for 50% of the required total battery backup time, as specified in the data schedule. |
| The input of the rectifier/charger shall be protected by a circuit breaker or fuses. The AC input shall be electrically isolated from the DC output. |
| The rectifier/charger shall be equipped with electronic current-limiting circuitry to limit the AC input current to 115% of the full load input current rating. |
| The rectifier/charger shall have an output filter to minimize ripple voltage into the battery. The maximum ripple voltage into the battery and inverter load shall not exceed 1% RMS, with or without the battery connected and from no load to full load output of the inverter. |
| The rectifier/charger shall be capable of continuously operating the inverter without the battery and without affecting the inverter output specified requirements. |
| The battery charger shall have sufficient capacity to recharge a fully discharged battery to a minimum 80% state-of-charge within 8 hours following an AC power failure, while carrying the full UPS system load. |
| The battery charger shall automatically equalize the partially discharged battery following an AC input line failure. The charger shall return to the float charge mode 8 hours (field adjustable) after the start of the equalize charging mode. |
| An automatic equalize battery charging logic shall be provided to manage battery-charging current and to automatically return to float charge mode in accordance with the battery manufacturer’s requirements. |
| Manual adjustments of battery equalize voltage, float voltage, and current limit adjustments shall be provided at the Operator panel. Adjustment of these settings with software is also acceptable. |
| Protective Devices The following shall be individually protected: a) AC Input to the rectifier/charger: by circuit breaker(s) or fuse(s) b) Battery disconnect: by fused disconnect switch or DC circuit breaker and shall have a facility to disconnect the battery from supplying its load upon reach of cell end of discharge voltage. Note: Buyer will furnish protective device for bypass AC line transformer input from the bypass AC line AC supply. |
| UPS Rectifier/Charger shall contain a programmable walk-in ramp circuit, for which input current shall gradually increase from 0 to UPS rated power in 10 seconds after the rectifier/charger input circuit breaker is closed. |
| UPS enclosure doors shall be hinged and designed to open at least 135 degrees, but preferably 180 degrees if possible, to facilitate maintenance access. |
| The charger shall be sized to provide a battery recharge time of 8 hours to at least 80% of battery capacity, as specified on the Data Schedule. |
| The charger shall include the following components as a minimum: a) Enclosure as specified in section 6.15 b) Input and output devices and features described in section 6.5 c) Controls and indications described in sections 6.6 through 6.7 d) Alarms and meters described in sections 6.8 thru 6.11 |
| The input to the rectifier/charger bridge shall be through shielded isolation transformer have its primary winding electrically isolated from its secondary winding and shall be varnish impregnated and baked to exclude moisture. The transformer construction shall be in accordance with the requirements of IEC 60726 or NEMA ST 20. |
| 180°C (class H) insulation system with an average winding temperature rise (measured by resistance) of 115°C. The hottest-spot winding temperature rise shall not exceed 145°C. |
| The temperature rise of transformer terminations used for making connections to cable shall not exceed 50°C in an ambient temperature of 40°C (90°C maximum total). |
Input Overcurrent Protection:
| An input circuit breaker shall be provided for overcurrent and short circuit protection, and also to provide a means of isolating the input power to the charger. The circuit breaker shall have an interrupting capacity equal to or greater than the available short-circuit current listed on the Data Schedule (14,000 amperes rms symmetrical minimum). Current-limiting fuses may be used to achieve the interrupting rating of the specified short-circuit current. Molded-case circuit breakers shall be designed and tested in accordance with UL 489 or IEC 60947. |
| Input Voltage: 120, 208, 240, or 480 volts, 50/60 Hz, single or three phase, or as specified on the Data Schedule. |
Input Surge:
| Input Surge: The input circuits of the charger shall have the input surge withstand capability specified in NEMA PE 5, Section 4.8 or IEC 60146. |
| The following control indications shall be provided on the front panel of the charger: a) “Charger On”/”Float Charge” – Green LED b) “Equalize Charge” – Amber or Yellow LED |
| A “Red” LED on the front panel of the charger cabinet shall provide the following Alarm indications: a) AC Input Failure b) Charger Failure c) Cooling Fan Failure (for forced ventilated units) d) Equipment Over-temperature e) Low Output Voltage – factory set at 5% below the float voltage setting f) Overload shutdown g) High Output Voltage h) Equalize Charge Mode i) Positive Ground Fault j) Negative Ground Fault k) Battery End of Discharge (Low DC Voltage Shutdown) Lead-Acid Battery: Set at 1.75 volt times the number of cells Nickel-Cadmium Battery: Set at 1.1 volt times the number of cells l) Battery Breaker Open. This alarm shall be activated from an auxiliary contact on the battery circuit breaker or battery disconnect switch (Buyer furnished). |
| A single pole double throw (normally open and normally closed) voltage free alarm contacts shall be provided for annunciating all of the alarms of Paragraph 6.8 as a common alarm to Buyer’s central alarm monitoring system. These alarms shall remain on for the duration of the alarm condition and shall automatically reset when the alarm condition is cleared. |
| Output Voltage and Current: A Digital (LED or LCD) panel meters shall be provided to display the output current and voltage readings. Meters shall have ± 1% full-scale accuracy. |
| Ground Fault Indication: The positive and negative ground faults shall be displayed on a common voltmeter via a switch to show the voltage from positive terminal to isolated ground and from negative terminal to isolated ground. The 3-position switch shall have a center off position. |
| Each component on the PCB shall be identified by etching or with a high temperature ink. Component identifications shall be as shown on the circuit schematic and PC board layout drawings. Exception: Miniature components and high density boards where component identifications may not be possible are exempt from this requirement. |
| Component leads shall not be utilized as through-board connection pins. |
| Components requiring manual adjustment shall be arranged to facilitate the required adjustments without removing the printed circuit card from its socket. |
| All PCB’s shall be coated to prevent atmospheric corrosion. |
| Power wiring shall be rated for 600 volts insulation. Control wiring shall be minimum 300 volts insulation. Conductors shall be stranded copper, 85°C minimum temperature rating, heat resistant and flame retardant. |
| All internal wiring shall be color-coded in accordance with equipment manufacturer’s standard. |
| Wiring brought out to terminal blocks shall be identified with slip-on type wire markers or with permanent printed characters. Snap-on or adhesive type markers are prohibited. Wire numbers and color codes shall correspond to the numbers and colors shown on the schematic/wiring diagram(s). |
| All inter-cabinet wires and cables shall be identified with thermoplastic slip-on wire markers with permanent printed characters or numbers. |
| Terminal blocks for user side shall contain 20% spare terminals. A maximum of two wires per point is permitted. |
| Power cable terminal connectors (lugs) shall be copper-bodied, compression (crimped) type suitable for stranded conductors. |
| Enclosures shall be either carbon steel or aluminum constructed in accordance with NEMA 250, Type 1 minimum, or IEC 60529, Type IP 21 minimum. |
| Enclosures shall be natural or force ventilated. Where forced ventilation is used, the enclosures shall be equipped with removable, easily cleanable, dust and vermin proof air filters. |
| Enclosures shall be designed for front access to all components and test points. Front access only is required. The Vendor shall advise the Buyer when front access only is not possible and if rear access is required for maintenance or for equipment cooling purposes. Non-front access designs require an approved waiver. |
| Enclosure door(s) shall be hinged, designed to open at least 120 degrees and easily removable for equipment maintenance. |
| Handles, screws and hinges shall be corrosion resistant. |
| Cabinets shall be designed for wall mounting or for free standing floor installation with other adjoining equipment on one or both sides. |
| Each enclosure shall be provided with a copper equipment grounding bus for connection to the Buyer’s equipment grounding conductor. The enclosure ground and the signal ground shall be connected to this ground bus. |
| The positive and negative DC buses shall be isolated from the earth ground. |
| Nameplates shall be in the English language according to American usage. |
| A stainless steel or aluminum nameplate shall be affixed to the charger cabinet with the following minimum information: 1) Manufacturer’s name and address 2) Equipment model and serial number 3) Input AC voltage, number of phases, and frequency 4) Nominal output DC voltage 5) Rated output current 6) Designed load kW and battery backup time 7) Buyer’s equipment tag number 8) Month and year of manufacture |
| Warning nameplates shall have white letters on a red background, in English and Arabic languages. |
| Exterior-mounted nameplates shall be attached with stainless steel or brass screws. Nameplates within the cabinet may be attached with permanent adhesive. |
| Major devices and components of the battery charger shall be provided with suitable nameplates or other permanent means of identifying the devices or components and their function. Abbreviations shall not be used to describe the item or its function. |
| Test points and diagnostic lights or via alphanumeric display shall be provided to facilitate adjustments and repairs. |
| Each system shall be provided with detailed Instructions Manual(s) including the following information as a minimum. The required number of sets shall be as specified on the Buyer’s Non-Material Requirements Form NMR-9597-1. a) Installation and commissioning instructions b) Operating instructions c) All items required by Paragraph 11.1 d) Service instructions with calibration and trouble shooting guide e) Wiring and schematic diagrams |
UPS/DC Battery Rectifier / Charger International Codes and Standards
| SAES-P-103 UPS and DC Systems |
| 17-SAMSS-514 Battery Charger / Rectifier |
| 17-SAMSS-516 Uninterruptible Power Supply System |